Computer for liquid level measurement

Abstract

A computer ( 20 ) adapted to communicate with a measuring apparatus ( 12 ) for receiving liquid level measurements and delivering a calibrated fuel quantity output ( 24 ) to a readout instrument ( 14 ). The computer ( 20 ) has an input interface ( 34 ) with a first input ( 22 A) for accepting a first liquid level measurement signal from said measuring apparatus ( 12 ). A first bias circuit ( 30 A) provides an adjustable offset bias to minimize voltage errors due to input bias current received in the first liquid level measurement signal ( 26 A). Computer( 20 ) also has a calibrating circuit ( 36 ) for calibrating the first liquid level measurement signal to provide a calibrated fuel quantity output signal ( 24 ) that can be read by readout instrument ( 14 ) through output interface ( 42 ).

What is claimed is:  
     
       1. A computer for receiving liquid level measurements from either Hall Effect or resistive float type transducers and delivering a calibrated fuel quantity output signal to a readout instrument within a vehicle, the computer comprising: 
       an input interface with a first input for accepting a first liquid level measurement signal from a first of said transducers;  
       a first bias circuit providing an adjustable offset bias to minimize voltage errors due to input bias current received in said first liquid level measurement signal;  
       a calibrating circuit wherein said first liquid level measurement signal is calibrated to provide said calibrated fuel quantity output signal that can be displayed by said readout instrument; and  
       an output interface between said calibrating circuit and said readout instrument.  
     
     
       2. The computer of  claim 1  wherein said input interface is further adapted to interact with a float resistive fuel transducer. 
     
     
       3. The computer of  claim 1  wherein said input interface is further adapted to interact with a Hall Effect fuel transducer. 
     
     
       4. The computer of  claim 1  wherein said input interface is further adapted to concurrently interact with both a resistive float fuel transducer and a Hall Effect fuel transducer. 
     
     
       5. The computer of  claim 1  wherein said measuring apparatus includes first and second transducers and wherein said input interface further comprises first and second inputs electrically coupled to said first and second transducers, respectively, for receiving corresponding first and second liquid level measurement signals. 
     
     
       6. The computer of  claim 5  further comprising a second bias circuit providing an adjustable offset bias to minimize voltage errors due to input bias current received in said second liquid level measurement signal. 
     
     
       7. The computer of  claim 6  further comprising a second gain circuit to adjust said second liquid level measurement signal to balance and match said first gain circuit. 
     
     
       8. The computer of  claim 7  further comprising a summing circuit to sum the first and second liquid level measurement signals of said first and second gain circuits, said summing circuit providing a summed output to said calibrating circuit. 
     
     
       9. The computer of  claim 8  wherein said summed output is calibrated by said calibrating circuit to provide said calibrated fuel quantity output signal to said readout instrument. 
     
     
       10. The computer of  claim 8  wherein said summing circuit provides an uncalibrated fuel quantity output signal to said output interface. 
     
     
       11. The computer of  claim 1  further comprising a first gain circuit to adjust said first liquid level measurement signal. 
     
     
       12. A liquid level measurement system for use in a vehicle comprising: 
       first and second transducers of the Hall Effect or restrictive float type, said transducers adapted to determine the level of liquid in one or more tanks of said vehicle and produce first and second liquid level measurement signals;  
       a computer for calibrating said first and second liquid level measurement signals, said computer including an input interface to said first and second transducers for receiving said first and second liquid level measurement signals, and a calibration circuit for producing a calibrated fuel quantity output signal; and  
       a readout instrument communicably coupled to said calibrated fuel quantity output signal of said computer for providing a readout representing a quantity of liquid in said tank.  
     
     
       13. The system of  claim 12  wherein said measuring apparatus further comprises a float resistive fuel transducer. 
     
     
       14. The system of  claim 12  wherein said computer further comprises: 
       said input interface with a first input for accepting said first liquid level measurement signal from said first transducer;  
       a first bias circuit providing an adjustable offset bias to minimize voltage errors due to input bias current received in said first liquid level measurement signal;  
       said calibrating circuit calibrating said first liquid level measurement signal to provide said calibrated fuel quantity output signal that can be displayed by said readout instrument; and  
       an output interface adapted to filtering out unwanted noise, wherein said calibrated fuel quantity output signal is output to said readout instrument.  
     
     
       15. The system of  claim 14  wherein said input interface further comprises a second input from said second transducer providing said second liquid level measurement signal. 
     
     
       16. The system of  claim 15  wherein said computer further comprises a second bias circuit providing an adjustable offset bias to minimize voltage errors due to input bias current received in said second liquid level measurement signal. 
     
     
       17. The system of  claim 16  wherein said computer further comprises a second gain circuit to adjust said second liquid level measurement signal to balance and match said first gain circuit. 
     
     
       18. The system of  claim 17  wherein said computer further comprises a summing circuit to sum the first and second liquid level measurement signals of said first and second gain circuits, said summing circuit providing a summed output to said calibrating circuit. 
     
     
       19. The system of  claim 18  wherein said summed output is calibrated by said calibrating circuit to provide said calibrated fuel quantity output signal to said readout instrument. 
     
     
       20. The system of  claim 18  wherein said summing circuit provides an uncalibrated fuel quantity output signal to said output interface. 
     
     
       21. The system of  claim 14  wherein said computer further comprises a first gain circuit to adjust said first liquid level measurement signal. 
     
     
       22. A method for determining a measurement of liquid level in one or more tanks of a vehicle that uses having first and second transducers producing first and second liquid level measurement signals, respectively, into a computer, said first and second transducers being of the Hall Effect or resistive float type, said computer providing an output to a readout instrument within said vehicle, the method comprising the following steps: 
       accepting said first and second liquid level measurement signals through an input interface;  
       adjusting the gain of said first and second liquid level measurement signals,  
       summing said first and second liquid level measurement signals to make a summed output; and  
       sending said liquid level measurement signal through an output interface to said readout instrument.  
     
     
       23. The method of  claim 22  wherein said step of adjusting the gain is preceded by the step of biasing the first and second liquid level measurement signals. 
     
     
       24. The method of  claim 23  wherein said step of summing said first and second liquid level measurement signals is followed by the step of calibrating the summed output.